Bourdon tube transducer

Abstract

A bourdon tube transducer has included a bourdon tube with a conductive plate electrically separated from the bourdon tube and in parallel with the bourdon tube. As the pressure varies, so does the electrical reactance between the bourdon tube and the conductive plate and this variation is used to vary the frequency of an electrical oscillator that is connected to the bourdon tube and the conductive plate.

I claim: 
     
       1. An environmental parameter transducer comprising: a bourdon tube means for sensing an environmental parameter at a remote port;   an electrical circuit controlled by the bourdon tube means;   means for providing an electrical reactance in the electrical circuit means, including an electrical conductive plate that has the same curvature as the bourdon tube means, of the same material as the bourdon tube means; and   means for retaining the conductor in a parallel configuration with the bourdon tube means separated therefrom by a preselected distance and electrically insulated therefrom.   
     
     
       2. The environmental parameter transducer according to claim 1 wherein the environmental parameter is temperature and the bourdon tube means comprises: a bourdon tube filled with a liquid and thermally connected to the remote port.   
     
     
       3. The environmental parameter transducers according to claims 1 or 2, further comprising: means for measuring the value of the reactance in the electrical circuit.   
     
     
       4. The environmental parameter transducers according to claim 3 wherein the means for measuring the value of the reactance in the electrical circuit comprises: an electrical oscillator connected in the electrical circuit such that the frequency of the oscillation is determined by the electrical reactance existing between the bourdon tube and the conductor.